Most new skis leave the plant without having their lower lateral edges sharpened, finished or ground. The present skis being more and more efficient, any imperfection, burr, scratch, etc. on the lower lateral edges of the skis leads to defects especially as regards the easiness of guiding the skis.
The ski edges are then sharpened in order to give them a good behavior on ice and frozen snow. This sharpening is in fact a machining of the lateral face of an edge by means of a tool such as an abrasive band or a file. This manual operation is tricky, because the angle of the edge which has just been sharpened should not be rounded off, and because said operation should not leave any scratch or score on the lower surface of the edge which would be prejudicial to a good guiding of the ski.